Module component

ABSTRACT

A module includes a component, a circuit board having the component mounted thereon, a first grounding pattern formed on an outermost periphery of a surface portion of the circuit board; a first sealer provided on the circuit board and having a dimension projected on the circuit board, and a metal film covering the sealer and connected to the grounding pattern. The dimension of the first dealer is smaller than an outside dimension of the circuit board. The first sealer is made of first resin and sealing the component. The module has a low profile and is adequately shielded.

TECHNICAL FIELD

[0001] The invention relates to a component module used for variouselectronic equipment and communications equipment.

BACKGROUND ART

[0002] A conventional component module illustrated in FIG. 9 includescircuit board 21 mounting component 23 at least on a side of the board,grounding electrode 24 having a recess shape formed on a side of circuitboard 21, and metal case 22 covering mounted component 23. Metal case 22has a terminal inserted and connected to grounding electrode 24 with asolder to electrically shield the module.

[0003] Since metal case 22 is soldered to the side of circuit board 21of the conventional component module, circuit board 21 needs to have athickness to support metal case 22. Metal case 22 may contact component23 mounted on circuit board 21, thus causing short-circuiting, or mayapply an external stress to the board, thus causing malfunction of acircuit. Therefore, metal case 22 is taller than component 23 foravoiding such incidents. Additionally, since the terminal of metal case22 is connected to a terminal component on the side of circuit board 21at several points, a clearance between circuit board 21 and metal case22 is needed for preventing metal case 22 from contact a circuit patternand component 23 on board 21. This structure prevents the module frombeing thin and from manufactured easily, and prevents the case fromproviding a sufficient shielding effect.

SUMMARY OF THE INVENTION

[0004] A module includes a component, a circuit board having thecomponent mounted thereon, a first grounding pattern formed on anoutermost periphery of a surface portion of the circuit board; a firstsealer provided on the circuit board and having a dimension projected onthe circuit board, and a metal film covering the sealer and connected tothe grounding pattern. The dimension of the first dealer is smaller thanan outside dimension of the circuit board. The first sealer is made offirst resin and sealing the component.

[0005] The module has a low profile and is adequately shielded.

BRIEF DESCRIPTION OF THE DRAWING

[0006]FIG. 1 is a perspective view of a component module in accordancewith Exemplary Embodiment 1 of the present invention.

[0007]FIG. 2 is a cross-sectional view of the module along line 2-2shown in FIG. 1.

[0008]FIG. 3 is a chart for comparing shielding effects of modules.

[0009]FIG. 4 is a cross-sectional view of another component module inaccordance with Embodiment 1.

[0010]FIG. 5 is a perspective view of a component module in accordancewith Exemplary Embodiment 2 of the invention.

[0011]FIG. 6 is a cross-sectional view of the module at line 6-6 shownin FIG. 5.

[0012]FIG. 7 is a cross-sectional view of another component module inaccordance with Embodiment 2.

[0013]FIG. 8 is an enlarged view of the module in accordance withEmbodiment 1.

[0014]FIG. 9 is a perspective view of a conventional component module.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Exemplary Embodiment 1

[0015]FIG. 1 is a perspective view of a component module in accordancewith Exemplary Embodiment 1 of the present invention. FIG. 2 is across-sectional view of the module at line 2-2 shown in FIG. 1. Circuitboard 1 is made of a multi-layer printed circuit board including atleast two wiring layers having a power supply circuit, a groundingpattern, and a high-frequency circuit formed on the layers. Components3, such as a resistor, a capacitor, a coil, a semiconductor, and acrystal connected to the board with lead-free solder are mounted oncircuit board 1. Sealer 4 made of epoxy resin has a dimension projectedon board 1 smaller than an outer dimension of circuit board 1 and isformed on circuit board 1 and covers components 3. Metal film 2 isprovided on sealer 4. Metal film 2 is connected to first groundingpattern 5 formed on four sides of an outermost periphery of a surfaceportion of circuit board 1.

[0016]FIG. 3 is a chart for comparing shielding effects of variouscomponent modules with reference to a component module which includessealer 4 and does not include metal film 3. Sample A is a conventionalcomponent module including a metal case. Sample B includes groundingpattern 5 at two shorter sides of circuit board 1. Sample C includesgrounding pattern 5 provided at four corners of circuit board 1. SampleD includes grounding pattern 5 provided at four sides of circuit board1. Sample E includes grounding pattern 5 provided at two longer sides ofcircuit board 1. Sample E, which includes grounding pattern 5 providedat four sides of circuit board 1, has a shielding effect larger thanthat of the conventional module including the metal case.

[0017] As shown in FIG. 3, the module covered with metal film 2connected to grounding pattern 5 provided at several points has a largeshielding effect. The module covered with metal film 2 connected togrounding pattern 5 provided at the four corners has particularly alarge shielding effect.

[0018] As shown in FIG. 2, metal film 2 is connected to groundingpattern 5 formed on the surface portion of the circuit board 1. Metalfilm 2 may be connected to a side of grounding pattern 5 formed on anouter periphery of circuit board 1, as shown in FIG. 4.

[0019] Metal film 2 having a thickness greater than about 1 μm providesa sufficient shielding effect. As illustrated in FIG. 8, metal film 101is formed by a non-electrolytic plating method with copper, and finermetal film 102 is formed by an electrolytic plating method, and thus,the films 101 and 102 provides the metal film 2. This structure allowsmetal film 2 to have a small contact resistance and stabilizes agrounding voltage at metal film 2, thus enhancing the shielding effect.

[0020] As shown in FIGS. 2 and 4, the dimension of sealer 4, which iscovered with metal film 4, projected on circuit board 1 is larger thanthe dimension of the circuit board. A step is formed between circuitboard 1 to sealer 4. The step improves adhesion between metal film 2composed of non-electrolytic plate and electrolytic plate and sealer 4or circuit board 1, preventing the metal film from being peeled off fromsealer 4 or grounding pattern 5. Thus, metal film 2 on sealer 4 which isconnected to grounding pattern 5 on circuit board 1 securely shields acircuit of circuit board 1 including components 3.

[0021] The components may be connected to the circuit board withlead-free solder, thus allowing the module to keep a connection of thecircuit when the module is mounted on a mother board and to keep theshielding effect.

[0022] The components may be connected to the circuit board withconductive adhesive, thus allowing the module to keep a connection ofthe circuit when the module is mounted on a mother board and to keep theshielding effect.

[0023] A clearance provided between the circuit board and the componentsmay be sealed with resin. The resin eliminates air in the clearance,thereby securing a reliability of the module and keeping the shieldingeffect.

Exemplary Embodiment 2

[0024]FIG. 5 is a perspective view of a component module in accordancewith Exemplary Embodiment 2 of the present invention. FIG. 6 is across-sectional view of the module at line 6-6 shown in FIG. 5. Asillustrated in FIG. 5, in the module in accordance with Embodiment 2,sealer 4 covered with metal film 2 is divided into three blocks bysealer 7 made of second resin.

[0025] As shown in FIG. 6, a power supply circuit, a ground pattern anda high-frequency circuit described in Embodiment 1 are formed on atleast two wiring layers of circuit board 1. First grounding pattern 5 isformed on an outer periphery of the circuit board.

[0026] Components 3, such as a resistor, a capacitor, a transistor, anda crystal are mounted on circuit board 1. Sealer 4 covering components 3has a dimension projected on circuit board 1 which is smaller than anouter dimension of circuit board 1 and is formed on circuit board 1.Sealer 4 has dividing ditch 6 provided therein for separating thecircuit board into circuit blocks.

[0027] Metal film 2 provided on sealer 4 and dividing ditch 6 isconnected to a surface of grounding pattern 5. Dividing ditch 6 isfilled with sealer 7 of the second resin on metal film 2.

[0028] As described, components 3 are separated into the blocks bydividing ditch 6. Each block is covered with sealer 4 and a portion ofmetal film 2 provided on each block. Metal film 2 is connected to firstgrounding pattern 5, so that each circuit block is electrically shieldedfrom other circuit blocks. This structure provides a small componentmodule including the circuit blocks protected from electrical noiseinterference of other blocks.

[0029] Dividing ditch 6 is filled with the second resin, forming sealer7 of the module. This structure provides a thin component module with alarge strength against bending, thus preventing the module from warping.This structure thus secures connection reliability between metal film 2and grounding pattern 5, and ensures an effective shielding performance.

[0030] In another component module shown in FIG. 7, metal film 2 coversthe sealer and the board to a depth within the thickness of circuitboard 1. The metal film shields a portion of patterns formed insidecircuit board 1, and provides a shielding effect larger than the moduleshown in FIG. 6.

[0031] Metal film 2 and grounding pattern 5 of the circuit board may beconnected either at a bottom or at a side of the dividing ditch ofsealer 4. This structure enhances a shielding effect for each circuitblock.

Industrial Applicability

[0032] A component module in accordance with the present invention has asmall size and has a high shielding effect.

1. A module comprising: a component; a circuit board having thecomponent mounted thereon; a first grounding pattern formed on anoutermost periphery of a surface portion of the circuit board; a firstsealer provided on the circuit board and having a dimension projected onthe circuit board, the dimension being smaller than an outside dimensionof the circuit board, the first sealer being made of firs first resinand sealing the component; and a metal film covering the first sealerand connected to the grounding pattern.
 2. The module according to claim1, wherein the surface portion of the circuit board is smaller than theouter dimension of the circuit board, and the metal film is connectedonto a side of the grounding pattern.
 3. The module according to claim1, further comprising a second grounding pattern provided on the surfaceportion of the circuit board, wherein the first sealer has a dividingditch formed therein corresponding to circuit blocks.
 4. The moduleaccording to claim 3, wherein the metal film is connected to the secondgrounding pattern through at least one of a bottom and a side of thedividing ditch.
 5. The module according to claim 3, further comprising asecond sealer made of second resin for filling the dividing ditch. 6.The module according to claim 1, wherein the metal film includes, afirst film plated on the first sealer by a non-electrolytic platingmethod, and a second film plated on the first film by an electrolyticplating method.
 7. The module according to claim 1, further comprising alead-free solder for connecting the circuit board to the component. 8.The module according to claim 1, further comprising a conductiveadhesive for connecting the circuit board to the component.
 9. Themodule according to claim 1, further including a third resin sealing aclearance between the circuit board and the component.